[buildkite] Fix periodic pipeline schedule yaml (#98042)

catalog-info.yaml

@@ -98,8 +98,8 @@ spec:
         build_pull_requests: false
         publish_commit_status: false
         trigger_mode: none
-  schedules:
-    Periodically on main:
-      branch: main
-      cronline: "0 0,8,16  * * America/New_York"
-      message: "Tests and checks that are run 3x daily"
+      schedules:
+        Periodically on main:
+          branch: main
+          cronline: "0 0,8,16  * * America/New_York"
+          message: "Tests and checks that are run 3x daily"